Smoking articles

ABSTRACT

The invention relates to smoking articles ( 10 ) comprising a rod of smokeable material ( 11 ) and a filter ( 12 ) attached to one end of the rod, said filter comprising at least two sections and being wrapped in a porous plug wrap, wherein a first tipping wrapper ( 14 ) overlies the join between the rod of smokeable material and the filter, and at least one additional tipping wrapper ( 15 ) is provided around the filter, spaced from and separate to the first tipping wrapper such that a portion of the porous plug wrap is exposed between the first and at least one additional tipping wrapper, and wherein the tipping wrappers are normally less porous than the plug wrap. However if the tipping wrappers are more porous than the plug wraps, the split tipping will still retain its functionality.

TECHNICAL FIELD

The present invention relates to smoking articles and, in particular, to smoking articles which reduce the machine measured yields of specific constituents or groups of constituents in mainstream smoke.

BACKGROUND

Conventionally, smoking articles such as cigarettes comprise a tobacco rod in the form of a cylinder of tobacco or tobacco-based smokeable material wrapped in a paper wrapper, which may be provided with a filter unit. In its basic form, the filter unit is a cylindrical element formed from filtration material such as cellulose acetate tow, optionally including features to modify the smoke flow and filter function, such as recesses and gaps, and additives such as particulate carbon. The tow may be wrapped in a layer of plug wrap which helps maintain the cylindrical shape and structure of the filtration material. The filter unit is joined to the tobacco rod using a tipping paper, which is an outer paper layer wrapped around the filter unit and overlapping the join between the filter unit and tobacco rod. The tipping paper is glued in place.

Tobacco smoke is a complex, dynamic mixture of more than 5000 identified constituents of which approximately 150 have been documented as being undesirable. The constituents are present in the mainstream smoke (MS) which is inhaled by a smoker and are also released between puffs as constituents of sidestream smoke (SS).

In 2001 the Institute of Medicine (TOM) reported that, since smoking related diseases were dose-related, and because epidemiologic studies show reduction in the risk of smoking related diseases following cessation, it might be possible to reduce smoking related risks by developing potential reduced-exposure products (PREPs). These they defined as: (1) products that result in the substantial reduction in exposure to one or more tobacco toxicants; and (2) if a risk reduction claim is made, products that can reasonably be expected to reduce the risk of one or more specific diseases or other adverse health effects (Stratton et al, 2001). To date, no combustible cigarette product has been shown to meet the general requirements outlined by the IOM.

There is, therefore, a challenge to provide a smoking article which shows significant reduction in emissions of all MS constituents considered to be undesirable. However, individual measures to reduce certain constituents will frequently give rise to no reduction in other constituents and, in some cases, even an increase in the levels of others.

In addition, it is also important to produce a product which is acceptable to the consumer. Much of the sensory impact of a conventional smoking article is based upon the constituents of the MS as well as other factors, such as pressure drop and number of puffs. It has been found that some measures taken to reduce certain MS constituents have the potential to provide the smoker with an unsatisfactory smoking experience.

SUMMARY OF THE INVENTION

In accordance with embodiments of the invention, a smoking article is provided comprising a rod of smokeable material and a filter attached to one end of the rod, said filter comprising at least three sections and being wrapped in a porous plug wrap, wherein a first tipping wrapper overlies the join between the rod of smokeable material and the filter, and at least one additional tipping wrapper is provided around the filter, spaced from and separate to the first tipping wrapper such that a portion of the porous plug wrap is exposed between the first and at least one additional tipping wrapper, and wherein the tipping wrappers are less porous than the plug wrap.

In some embodiments, at least one filter section comprises a fibrous filter material. At least one filter section may comprise a porous absorbent material. At least one filter section may comprise an ion exchange resin.

In certain embodiments, the porous adsorbent material which may be included in at least one filter section is a porous carbon with an engineered porous structure. The filter section may include from about 20 mg to about 80 mg of the porous adsorbent material.

In certain embodiments, the ion exchange resin which may be included in at least one filter section has a surface activated amine. The filter section may include from about 5 mg to about 40 mg of the ion exchange resin.

In some embodiments, the filter comprises a mouth end section comprising a fibrous filter material, a section comprising an ion exchange resin and a section adjacent the rod of smokeable material comprising porous adsorbent material.

In some embodiments the filter is longer than the filter in a conventional cigarette, having a length from about 30 mm to about 40 mm, preferably about 37 mm.

In some embodiments the smoking article has an overall length, including the filter and the rod of smokeable material, of about 83 mm.

In some embodiments the smoking article has a smaller circumference than that of a conventional cigarette, having a circumference of about 21 mm

In some embodiments, the gap between the first and at least one additional tipping wrapper is about 10 mm wide.

In some embodiments, the smoking article further includes ventilation holes formed in a tipping wrapper and/or in the body of the filter.

In some embodiments, the rod of smokeable material comprises one or more of:

-   -   (a) a tobacco treated to produce reduced levels of nitrogenous         compounds;     -   (b) a tobacco treated to remove polyphenols and/or peptides;     -   (c) a tobacco substitute sheet comprising a non-combustible         inorganic filler, a binder and an aerosol generating means.

In addition, the smokeable material may further comprise lamina tobacco and/or dry ice expanded tobacco (DIET).

Furthermore, in some embodiments, the smokeable material further comprises glycerol. The smokeable material may also or alternatively comprise at least one flavour.

In some embodiments, the smokeable material of the smoking article comprises a blend treated tobacco, tobacco substitute sheet, DIET, lamina tobacco, glycerol and a top flavour.

BRIEF DESCRIPTION OF FIGURES

Embodiments of the invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a smoking article according to an embodiment of the invention;

FIG. 2 is an exploded view illustrating the interior structure of the filter of FIG. 1 in more detail;

FIG. 3 is a schematic illustration of a longitudinal cross-sectional view of a smoking article according to an alternative embodiment of the invention;

FIG. 4 shows a summary of the process by which high activity polymer-derived carbon is prepared; and

FIG. 5 shows vent flow measurements for varying ventilation systems.

DETAILED DESCRIPTION

The present invention relates to smoking articles including a filter design which provides an enhanced ventilation system to provide a smoking article with increased toxicant reductions whilst retaining consumer acceptability.

According to some embodiments, toxicant reductions can be further enhanced by combining the filter with bespoke tobacco blends and/or bespoke adsorbent filter additives. In addition, an optional new overall smoking article format can assist in balancing the effects of the filter design and other toxicant reduction measures to enhance the consumer acceptability of the smoking article.

In a standard or conventional cigarette the filter and tobacco rod are joined by a tipping wrapper which covers the entire length of the filter and the adjacent end of the tobacco rod. Where ventilation is provided, this tends to be in the form of holes or channels formed in the tipping paper, to allow ambient air to be drawn into the filter and to dilute the MS.

In embodiments of the present invention, the tipping wrapper does not cover the entire filter. Rather, the tipping paper is split and/or comprises two or more strips. A first tipping wrapper covers the join between the filter and rod of smokeable material, for example to attach the filter to the rod. At least one additional tipping wrapper surrounds another part of the filter, spaced from and separate to the first tipping wrapper such that a gap is formed between the first and at least one additional tipping wrapper. This gap exposes an area of the filter which is surrounded with a material which is more porous than the tipping wrappers. This results in a section of the filter which is surrounded only by a porous (plug wrap) paper, allowing increased diffusion of gases into and out of the filter area. For example, gases such as CO (carbon monoxide) and NO (nitric oxide) may diffuse out of the filter from this filter area. This so-called ‘split tipping’ can also improve vent level control at higher flow rates.

Referring now to FIGS. 1 and 2, a smoking article 10 according to an embodiment of the invention is shown comprising a rod of smokeable material 11 and a filter 12. In one embodiment, the smokeable material rod 11 comprises a cylinder of smokeable tobacco or tobacco-based material contained within a paper sleeve.

The rod of smokeable material 11 is attached to a filter 12. In the illustrated embodiment, a first tipping wrapper 14 is positioned to overlay the join between the rod of smokeable material 11 and the filter. This tipping wrapper 14 helps to attach the rod 11 to the filter 12. An additional tipping wrapper 15 surrounds the filter at the mouth end 13 of the filter. The tipping wrappers 14, 15 are positioned spaced from and separate to one another to provide a gap 16 between them. This gap 16 is a section of the filter which is not surrounded by a tipping wrapper. In the illustrated embodiment, this section of the filter at the gap 16 is surrounded by an exposed porous plug wrap.

The structure of the filter 12 is illustrated in more detail in the exploded view of FIG. 2. The filter comprises three separate filter sections 21 a, 21 b, 21 c. Each individual filter section 21 a, 21 b, 21 c is preferably different. In order that each individual filter section 21 a, 21 b, 21 c retains the desired structure, they may optionally be each individually wrapped in an individual inner plug wrap 22 a, 22 b, 22 c.

Once positioned together end-to-end, the three individually wrapped filter sections 21 a, 21 b, 21 c are then wrapped together with a single outer plug wrap 23 which holds them together as a single unit. The outer plug wrap 23 is made of a porous material, and at least some of the individual inner plug wraps 22 a, 22 b, 22 c may also be porous.

The filter 12 is attached to the tobacco rod 11 by the first tipping wrapper 14 which is wrapped around the tobacco rod 11 and the filter 12 so that it overlies the join therebetween. The tipping wrapper is glued in place.

A second, separate tipping wrapper 15 is wrapped around the mouth end 13 of the filter 12 distal to the tobacco rod 11, and is spaced from the first tipping wrapper 14 to leave a gap 16 therebetween. The outer plug wrap 23 is exposed in the gap 16 to define a ventilation area in the filter section of the smoking article 10. The porosity of this section of the filter will be determined by the porosity of the outer plug wrap 23 and any inner plug wrap surrounding the filter in that area. The tipping wrappers preferably provide areas of reduced porosity compared to the porosity of the paper surrounding the section of the filter aligned with the gap 16 between the tipping wrappers 14, 15.

In the embodiment of the invention illustrated in FIGS. 1 and 2, the filter 12 is described as comprising three separate sections 21 a, 21 b, 21 c. However, it will be appreciated that more than three filter sections may be provided within the scope of the invention. Furthermore, the invention is not intended to be limited to each individual filter section 21 a, 21 b, 21 c being first wrapped in its own individual plug wrap 22 a, 22 b, 22 c, and instead, the outer plug wrap 23 may serve to hold all of the filter sections together and in their preferred form, which may be cylindrical.

In the embodiment shown in FIG. 2, the three filter sections 21 a, 21 b, 21 c are not of equal size. In the illustrated embodiment, the mouth end section 21 c is shorter than the middle section 21 b, which in turn is shorter than the section 21 a adjacent the rod of smokeable material. In a particular embodiment, the mouth end section 21 c is 7 mm in length, the middle section 21 b is 10 mm in length and the section 21 a adjacent the rod of smokeable material is 20 mm in length.

The first and second tipping wrappers 14, 15 are sized and positioned to expose part of the section 21 a adjacent the rod of smokeable material. The second tipping wrapper 15 at the mouth end of the filter is wider than the first tipping wrapper 14. In the particular embodiment illustrated in FIG. 2, the first tipping wrapper covers an area 11 mm wide, overlying the end of the rod of smokeable material and part of the adjacent filter section 21 a. Specifically, the first tipping wrapper 14 may overlay 5 mm of the rod of smokeable material and 6 mm of the adjacent filter section 21 a. The gap between the first tipping wrapper 14 and the second tipping wrapper 15 in the illustrated embodiment is 10 mm. Again in the embodiment illustrated in FIG. 2, the second tipping wrapper covers an area 21 mm wide at the mouth end of the filter 12, overlying all of the mouth end filter section 21 c, all of the central filter section 21 b and a portion (4 mm) of the filter section 21 a adjacent the rod of smokeable material. Thus, the gap 16 between the first and second tipping wrappers 14, 15 is aligned with a portion of the filter section 22 a adjacent the rod of smokeable material 11.

Variations are possible from the above described smoking article 10 within the scope of the invention. For example, more than two separate tipping wrappers may be provided circumscribing the filter and/or rod of smokeable material and they may be positioned so as to provide two or more gaps. The size (width) of the wrappers and their positions may vary to provide gaps of varying width and at varying positions. In addition, the number and sizes of the filter sections may also vary.

FIG. 3 shows an alternative embodiment of the smoking article, wherein the filter 112 further includes ventilation holes 131. The smoking article 110 comprises the same components as the smoking article 10 illustrated in FIG. 2, with the exception that it includes ventilation holes 131.

The purpose of ventilation holes is to allow air to enter the filter when a smoker draws on the smoking article. The air mixes with and dilutes the mainstream smoke and other components drawn through the filter from the ignited smokeable material. There are a range of techniques currently used for making ventilation holes. The tipping wrapper may be pre-perforated before wrapping by a mechanical or electrostatic perforating device or by a laser beam. Alternatively, a laser beam may be used to make the holes after the smoking article has been assembled, using an on-line or on-machine-line system. In the latter case, the holes are burnt into the filter by the focused laser beam, and hence pass through the paper or papers wrapped around the filter (tipping wrapper and plug wrap) and into the material within the filter.

The location of the holes along the filter length can modify the filtering and dilution effects, in particular if the holes are positioned with reference to individual components of a multi-segment filter. In smoking articles having the above described “split tipping”, this split tipping has been found to improve vent level control at higher flow rates.

The vent flow measurements for three different ventilation systems are depicted in FIG. 5. Plot A shows data for a test cigarette where all of the filter ventilation is produced by split tipping, with a 20 mm split gap. Plot B shows data for a commercial control cigarette with on-machine laser (OML) ventilation on the filter. Plot C shows data for a test cigarette where part of the ventilation is produced by slit tipping (with a 10 mm gap) and partly by an OML zone in the filter.

Under ISO machine puffing conditions, i.e. at an average ISO flow rate drawn through a cigarette of 17.5 cm³ per second (or 1.050 L/min), filter ventilation is measured as the percentage air which flows in through the ventilation holes on the cigarette filter relative to the total puff volume, or average flow drawn through the cigarette. The ventilation level that is achieved influences the ISO yields of tar, nicotine and CO from the product. When consumers smoke cigarettes they may take larger puff volumes and/or draw at greater flow rates through the cigarette relative to ISO. Therefore, consumers may take yields from conventional cigarettes in excess of the ISO machine smoked values; one of the reasons for this increase in yield is that the effective ‘filter ventilation’ is reduced at draw rates above ISO (as depicted by Plot B in FIG. 5).

In contrast, with the ‘split tip’ system of ventilation (with no additional ventilation holes), as the flow rate through the cigarette is increased above the ISO flow rate the ‘effective ventilation’ is not reduced to the degree that would be expected in conventional products. In fact the flow versus pressure drop relationship through the ‘split tip’ area is almost linear such that as the flow in the cigarette rod is increased the flow through the ‘split tip’ increases almost in the same proportion. Therefore, there is very little loss in ‘effective ventilation’ under more intense smoking (see Plot A in FIG. 5).

It should be obvious to those skilled in the art that split tipping is only effective at influencing yields from human or machine smoking when the ventilation zone is not blocked. This means that split tipping is not effective using the Health Canada Intense smoking (machine) regime.

As it is difficult to predict the exact level of ventilation that can be achieved due to split tipping alone some trial samples were manufactured and on-machine laser used to ‘fine tune’ the sample filter ventilation and achieve the required ISO yields (for example, used in generating Plot C of FIG. 5). As seen in this plot the effect of split tipping is evident using the combined ventilation system.

In the embodiment illustrated in FIG. 3, the ventilation holes 131 are positioned annually around the circumference of the filter 112, having been burnt by a focused laser beam (an On Machine Laser). The holes extend through the tipping wrapper 115, through the underlying plug wrap 123 and any optional inner plug wrap (not shown), and a short distance into the filter body.

Ventilation holes may be arranged as a row or zone around the circumference of the filter, approximately 11 to 16 mm from the mouth end of the filter. In the particular embodiment illustrated, the ventilation holes 131 are provided 13 mm from the mouth end 113 of the filter 112. This means that the ventilation holes 131 are aligned with the central filter section 121 b.

Ventilation holes made by laser typically have a depth of the order of 1 to 2 mm, although they may extend further into the body of the filter, having a depth of greater than 2 mm, for example a depth of 2 to 3.5 mm and/or a depth that is at least 25% of the diameter of the filter, or even 25 to 50% of the diameter of the filter. In some embodiments, the smoking article comprises at least one ventilation hole extending though a tipping wrapper and any plug wrap into the filter. The hole may extend to a depth such that air drawn in through the ventilation hole enters a central region of the filter. Alternatively, one or more holes may be provided and arranged to control the passage of the diluting air through the filter. For example, the holes may be of varying depths or may be aligned with predetermined parts of the filter.

Conventional cigarettes typically include cellulose acetate (CA) tow as a filter material. The cellulose acetate is usually treated with plasticizers which bind adjacent fibres at their points of contact, giving the fibrous tow increased strength and structural integrity. Suitable plasticizers for this use include triacetin (glycerin triacetate), TEC (triethyl citrate) and PEG 400 (low molecular weight polyethylene glycol). Plasticized cellulose acetate tow is also known to improve the selective removal of semi-volatile compounds found in smoke (e.g. phenol, o-cresol, p-cresol and m-cresol). In some embodiments of the invention, at least one of the filter sections includes cellulose acetate. In some embodiments, the mouth end filter section (illustrated as filter section 21 c in FIG. 1) comprises or consists essentially of cellulose acetate tow, and preferably plasticized cellulose acetate tow.

Whilst fibrous filter material is able to reduce the particulate phase constituents with the tar and nicotine, little selective reduction occurs. What is more, since cellulose acetate filters have little or no effect on volatile constituents, increasing filtration efficiency increases the ratios of their yields relative to tar and nicotine. However, the presence of a cellulose acetate filter section can enhance the consumer acceptability of the smoking articles of the present invention and this may be especially the case where the cellulose acetate filter section is positioned at the mouth end of the filter.

In order to further enhance the adsorption characteristics of the filter of the smoking articles, porous adsorbents may be included in order to remove some of the volatile constituents from the mainstream smoke. Active Carbon (AC) is a non-selective adsorbent which is widely used in cigarette filters and can reduce a broad range of volatile smoke constituents to a significant extent via physisorption.

The adsorption characteristics of the porous carbon may be enhanced by engineering the porous surface of the carbon, to provide what may be called “High Activity Carbon” (HAC). Thus, in some embodiments of the invention, at least one section of the filter comprises high activity carbon.

The high activity carbon may be incorporated into a filter section of a smoking article in a cavity, or dispersed (“Dalmatian” style) throughout a plug of filter material (such as cellulose acetate). In some embodiments, the high activity carbon may be applied to the inner surface of the (inner) plug wrap of the filter section, thereby lying between the plug wrap and the plug of filter material.

In some embodiments, the filter section adjacent the rod of smokeable material (illustrated as section 21 a in FIG. 1) comprises high activity carbon. In some embodiments, a filter section is loaded with between 20 and 80 mg, and preferably with about 50 mg, high activity carbon.

The high activity carbon may be polymer-derived. For example, it may be a porous carbon bead material derived from polystyrene.

One possible type of high activity carbon that may be used in the smoking articles of the invention comprises substantially spherical particles of polymer-derived carbon has been prepared by a proprietary process (Von Blucher and De Ruiter 2004; Von Blucher et el 2006; Böhringer and Fichtner 2008) and is available from Blucher GmbH (Germany).

These polymer-derived, high activity carbon granules possess a pore structure which is different from the carbon commonly used in commercial cigarettes, which is typically derived from coconut shells. As a result it has superior adsorption characteristics for a range of volatile smoke toxicants. The polymer-derived carbon performs well under both ISO and HCI smoking regimes and with regular and smaller circumference cigarettes, although some limitations have been observed under higher flow-rate smoking conditions in the removal of acetaldehyde.

The process used to prepare the polymer-derived carbon is depicted in FIG. 4. The polymer-derived active carbon is produced using a batch process with indirect heated rotary kilns, under reduced pressure in an inert atmosphere. After preparation of the spherical polymer feed-stock the material is thermally stabilised using an excess of oleum. Subsequently, the material is slowly heated to 500° C., resulting in the release of predominantly SO₂ and H₂O and the carbonisation of the polymer. The resulting carbon has an initial pore system which is not accessible for typical adsorptives. To create a porous system suitable for adsorption, the material is further heated to about 900 to 1000° C. for activation with oxidising agents (steam). This establishes a pore system consisting mainly of micropores with pore sizes between 0.7 and 3 nm. Subsequent activation with CO₂ leads to the formation of predominantly larger mesopores in the range of 3 to 80 nm. Combining the steam and CO₂ activation steps offers a flexible strategy for producing desired pore characteristics.

The polymer-derived carbon, being a synthetic material, possesses a much more closely defined spherical shape, together with a more uniform particle size. The polymer-derived material possesses a lower density, and has a lower ash content reflecting the synthetic nature of the polymer feedstock in comparison to a natural coconut shell as starting materials for the carbonization processes.

Most smoke constituents are adsorbed more effectively by the polymer-derived carbon under the ISO regime than by activated coconut carbon, with reductions of the order of 80-95% observed with smoke constituents other than formaldehyde, acetaldehyde, hydrogen cyanide (HCN) and toluene (50-60% reductions). Under HCI conditions, cigarettes with conventional coconut carbon provide reductions of the order of 25-45% for most smoke constituents, other than acetaldehyde (16%). The cigarettes including polymer-derived carbon reduce most smoke constituent yields by 60-90%, other than acetaldehyde and HCN (15-30%).

Chemisorption is also capable of removing toxicants from mainstream smoke, including high volatility aldehydes and HCN. An amine-functionalised resin offers the potential for the nucleophilic capture of aldehydes from mainstream smoke, and due to its weakly basic nature it may also be used for the removal of HCN from mainstream smoke.

Thus, in some embodiments of the invention, at least one section of the filter comprises an ion exchange resin. The ion exchange resin has a surface activated amine which may bind effectively to selected vapour phase aldehyde constituents and hydrogen cyanide.

The amine-functionalised resin material may be incorporated into a filter section of a smoking article in a cavity, or dispersed (“Dalmatian” style) throughout a plug of filter material (such as cellulose acetate). In some embodiments, the amine-functionalised resin may be applied to the inner surface of the (inner) plug wrap of the filter section, thereby lying between the plug wrap and the plug of filter material.

In one possible arrangement, the central filter section is loaded with between 5 and 40 mg, and preferably about 20 mg, of an amine-functionalised resin.

DIAION® CR20 is a commercially available type of amine-functionalised ion exchange resin bead (manufactured by Mitsubishi Chemical Corporation). It has polyamine groups as chelating ligands which are bonded onto a highly porous crosslinked polystyrene matrix. CR20 shows large affinity for transition metal ions. The exact type of amine groups produced by functionalisation cannot be precisely controlled and several different types could be present on the resins.

Commercial grade CR20 (hereafter referred to as CR20C) was found to have a characteristic odour which is incompatible with conventional consumer acceptable cigarette smoke character when incorporated into cigarettes. However, modification to the synthesis conditions by Mitsubishi significantly reduced the intensity of this odour, resulting in a “low-odour” grade of CR20 (hereafter referred to as CR20L). In this work, unless otherwise stated, all results obtained refer to CR20L. This material possessed a bead size of 600 mm, density of 0.64 g/cm³, a 15% by weight water content, and total exchange capacity of 0.92 meq/cm³. Various other types of CR20 are made by Mitsubishi Chemical Corporation, including CR20D and CR20HD and these may be suitable for use in smoking articles.

Some CR20 beads are provided in water and, in order to make them suitable for use in a cigarette filter application, it may be necessary to remove at least some of the water. In some embodiments, the water is removed and the material is dried to approximately 15% or less moisture. In alternative embodiments, a higher moisture content are also acceptable in the filter of smoking articles.

CR20, including specifically CR20L, may be incorporated into the filters of smoking articles of the present invention. In comparison to filters containing conventional carbon, CR20L offers superior reductions for HCN, formaldehyde and acetaldehyde.

In some embodiments, of the present invention, the smoking articles are based upon a novel format. This may, in part, be in order to accommodate the longer filter according to some embodiments described herein. For example, in some embodiments the smoking articles comprise three or more filter sections with a total length of approximately 37 mm, the tipping length (that is, the distance from the mouth end of the smoking article to the furthermost edge of tipping wrapper) is 42 mm. A conventional king size cigarette will generally have a 15 to 27 mm filter. The extended length of the filter of some of the smoking articles of the invention results in the dual effect of increased smoke filtration due to the longer residence time of the smoke in the filter and there being less smokeable material to be combusted due to reduced length of the smokeable material rod.

In some embodiments, the filter has a length of at least 30 mm, 31 mm, 32 mm, 33 mm, 34 mm or at least 35 mm. Alternatively or in addition, the filter may have a length of no more than 50 mm, 49 mm, 48 mm, 47 mm, 46 mm, 45 mm, 44 mm, 43 mm, 42 mm, 41 mm, or no more than 40 mm.

To counterbalance this decrease in smokeable material rod length, a slow burning paper wrapper may be used to circumscribe the rod of smokeable material. This can enable the smoker to achieve the same number of puffs per smoking article as with a conventional length rod of smokeable material.

In alternative embodiments, the smoking article may be provided with a rod of smokeable material which has the same or a similar length as the rod of smokeable material in a conventional cigarette. This will render the smoking article longer than a conventional cigarette, as a result of the longer filter.

In some embodiments, the smoking article has a so-called “demi slim” circumference of 21 mm compared with the standard “king size” circumference of 24.6 mm. The smoking articles may have a standard “king size” length of 83 mm (including both the rod of smokeable material and the filter).

In addition to the modifications made to the filter of the smoking articles in order to enhance the reduction in toxicants present in the mainstream smoke, further technologies relating to the smokeable material may be used, to complement the effects of the filter or to counterbalance them where desired.

Treated tobacco blends are described herein which have been treated by processes that allow the removal of protein and polyphenols from tobacco, with a beneficial effect on the smoke toxicant yields. The tobacco treatment may be carried out on cut, flue-cured tobacco. Briefly, the tobacco blend is subjected to an aqueous extraction step and the extract is subsequently passed through two stages of filtration to remove polyphenols and soluble peptides. The residual tobacco solids are treated with protease to remove insoluble proteins. After washing and enzyme deactivation, the tobacco solids and filtered aqueous extract are re-combined. The treatment process results in material referred to herein as blend treated tobacco (BTT), which results in reduced smoke yields of phenolics, aromatic amines, HCN, and a number of other nitrogenous smoke constituents; however, there are also increases in the yields of formaldehyde and isoprene. The blend treated tobacco retains the structure of the original tobacco and may be incorporated into rods of smokeable material for inclusion in smoking articles using conventional cigarette making equipment, without the need for reconstitution into a sheet material.

In some embodiments of the invention, the smokeable material comprises a blend treated tobacco.

The tobacco material to be extracted may be strip, cut, shredded or ground tobacco. In some embodiments, the tobacco is shredded tobacco. Other forms of tobacco may, however, be extracted using the methods described herein.

The tobacco material may be mixed with a solvent for extraction to form a slurry. The solvent may be added to the tobacco material in a ratio of between 10:1 and 50:1, preferably between 20:1 and 40:1 and most preferably between 25:1 and 30:1 by weight. In one embodiment, the solvent is added to the tobacco material in a ratio of 27:1 by weight.

The solvent may be an organic solution, but preferably is an aqueous solution or is water. At the very start of the extraction process, the solvent is usually water, but it can also contain alcohols such as ethanol or methanol, or it can contain a surfactant. Other solvents could be used, depending on the particular constituents to be extracted from the tobacco.

The extraction may be performed at about 15-85° C., and preferably is performed at about 65° C. It is preferable for the slurry to be continually stirred during extraction, such that the tobacco remains in suspension. Extraction should be performed for between 15 minutes and two hours. In a preferred embodiment, extraction is performed for approximately 20 minutes.

During extraction, soluble tobacco components are removed from the tobacco material and enter solution. These include nicotine, sugars, some proteins, amino acids, pectins, polyphenols and flavours. Up to about 55% of the initial tobacco weight may become solubilised. It is important that the pectins in the tobacco fibre remain cross-linked throughout the extraction and treatment process in order to maintain the fibrous structure of the tobacco. Accordingly, calcium may be added to the solvent used to extract the tobacco and to any solutions used in the downstream processing procedures.

Following extraction, the slurry may be drained to allow the liquid filtrate (the “mother filtrate”) to be collected. Meanwhile, the insoluble tobacco residue may be further extracted by counter-current washing as it is conveyed, so that as many soluble constituents as possible are removed from the tobacco.

Fresh solvent may be applied to the tobacco and the filtrate (the “wash filtrate”) is collected. The wash filtrate may be recycled by being applied to the incoming tobacco residue travelling on the belt at an upstream point. The collection and upstream reapplication of wash filtrate to incoming tobacco residue may be repeated a number of times, preferably three, four or even five times. Thus, the final wash filtrate that is collected at the head of the belt may be concentrated in those soluble tobacco constituents that have been removed from the tobacco residue as it travels the length of the filter. The final wash filtrate may be further recycled by being added to fresh tobacco to form a tobacco slurry, ready for extraction. For example, the final wash filtrate may be added into the tobacco mix tank where a tobacco slurry is formed prior to extraction. The extraction process may thus be a continual process in which fresh tobacco is extracted using recycled wash filtrate. Only at start-up of this extraction process is tobacco extracted with fresh solvent. Once the extraction process has begun, no fresh solvent is used in the extraction, but the solvent is solely made up of recycled wash filtrate.

As the extraction process continues, the extract thus becomes more concentrated in soluble tobacco constituents. These constituents include those that entered solution during primary extraction in the extraction tank (forming the mother filtrate), as well as those that entered solution during secondary extraction on the horizontal belt filter (forming the wash filtrate).

The final filtrate thus comprises both the mother and wash filtrates. In so doing, the tobacco residue that results after filtration is devoid of those constituents that are soluble in the solvent used for extraction. The extracted tobacco may be squeezed at the end of filtration, so as to remove any excess liquid from it. The extracted tobacco emanating from the horizontal belt filter is thus typically in the form of a dewatered mat.

The final filtrate, hereinafter referred to as the tobacco extract, may be subsequently processed to remove those constituents not desired in the final tobacco product. Undesirable constituents include proteins, polypeptides, amino acids, polyphenols, nitrates, amines, nitrosamines and pigment compounds. The levels of constituents which may be considered desirable, such as sugar and nicotine, may, however, remain unaffected so that the flavour and smoking properties of the extracted tobacco are comparable to those of the original material.

In a preferred embodiment, the tobacco extract is treated to remove proteins, polypeptides and/or amino acids. Up to 60% of the proteins contained in the original tobacco material may be removed using an insoluble adsorbent such as hydroxyapatite or a Fuller's Earth mineral such as attapulgite or bentonite. The tobacco extract is preferably treated with bentonite, to remove polypeptides therefrom. Bentonite may be added to the extract in an amount of 2-4% of the weight of tobacco initially extracted. Alternatively, the tobacco extract may be fed into a tank containing a slurry of bentonite in water. A suitable slurry contains approximately 7 kg of bentonite in approximately 64 kg water (quantities per hour), for example, 7.13 kg bentonite in 64.18 kg water (quantities per hour). In any case, the bentonite concentration should be high enough to substantially reduce the protein content of the tobacco extract, but not so high as to additionally adsorb nicotine from it. Bentonite treatment may also be effective in the removal of pigment compounds found in tobacco extract which, if not removed, tend to darken the extract after concentration. When sufficient bentonite is used to treat the extract, the reduced amount of pigment compounds may result in a product that is not overly darkened in appearance.

Following bentonite treatment, the tobacco extract may be purified from the slurry by centrifugation and/or filtration. The tobacco extract may also, or alternatively, be treated to remove polyphenols therefrom.

Polyvinylpolypyrrolidone (PVPP) is an insoluble adsorbent for polyphenols, traditionally used in the brewing industry to remove polyphenols from beer. PVPP in an amount of 5-10% of the weight of tobacco initially extracted may be added to the extract. This amount of PVPP is capable of removing between 50 and 90% of the polyphenols in solution. The optimum pH for removal of polyphenols from the tobacco extract by PVPP is believed to be about 3. The efficiency of adsorption by PVPP may therefore be increased by reducing the pH of the extract via the addition of a suitable acid, such as hydrochloric acid.

As an alternative to using PVPP to adsorb the polyphenols, one or more enzymes may be added to the tobacco extract to degrade the polyphenols therein. A suitable enzyme is laccase (urishiol oxidase). The invention is not, however, limited to methods for removing only proteins and/or polyphenols from tobacco. Alternative or additional enzymes, agents or adsorbents may be used to remove other undesirable tobacco constituents from the tobacco extract. Examples of further undesirable tobacco constituents that could be removed from the extract include nitrates, amines and nitrosamines.

If a plurality of constituents is to be removed from the tobacco extract, a number of tanks may be set up in series, each one comprising a different enzyme, agent or adsorbent, in order for a chosen complement of undesirable constituents to be removed. Alternatively, a single tank may contain a plurality of enzymes, agents or adsorbents so that the undesirable constituents may be removed in a single step. For example, a bentonite or PVPP holding tank could comprise one or more additional enzymes, agents or adsorbents so as to remove not only protein or phenols from the tobacco, but one or more further undesirable constituents also.

Following treatment of the tobacco extract to remove the selected undesirable constituents, the extract is preferably concentrated to a solids concentration of between 20 and 50% by weight. Concentrations of up to 10% solids are most efficiently achieved using reverse osmosis. A further concentration to approximately 40% solids may be achieved by means of a falling film evaporator. Other methods of concentration can be used and will be known to a person skilled in the art. The concentrated tobacco extract may be subsequently recombined with the extracted tobacco.

The tobacco, having been extracted in an aqueous solution as discussed above, however, is preferably further extracted to remove one or more further undesirable constituents before being recombined with the concentrated tobacco extract. Further extraction of the tobacco may be performed using an enzyme specifically selected for removal of the constituent of choice. In a preferred embodiment, the enzyme is a proteolytic enzyme for removal of protein from the tobacco. The enzyme is preferably a bacterial or fungal enzyme and, more preferably, is an enzyme used commercially in the food and detergent industries. The enzyme may be selected from the group consisting of Savinase™, Neutrase™, Enzobake™ and Alcalase™, which are all available from Novozymes A/S. The proteolytic enzyme is preferably added to the tobacco in an amount of between 0.1 and 5% by weight of the tobacco material. For example, Savinase™ may be added to the tobacco in an amount of approximately 1% by weight. The tobacco may be reslurried in a solution of the chosen enzyme. The ratio of water to tobacco in the slurry should be between 10:1 and 50:1, preferably between 20:1 and 40:1 and most preferably between 25:1 and 30:1 by weight. In a particularly preferred embodiment, the ratio of water to tobacco is 27:1 by weight.

The pH of the tobacco/enzyme mixture should be that which promotes optimal enzyme activity. Accordingly, it may prove convenient to feed the dewatered mat of tobacco into a tank in which the pH is adjusted, for example, by the addition of a base such as sodium hydroxide. The pH-adjusted tobacco may then be fed into an enzyme dosing tank for mixing with the enzyme of choice. The tobacco/enzyme mixture may subsequently be fed into a plug flow reactor, where the enzymic extraction is performed. The enzymic extraction should be carried out at the temperature promoting optimal enzyme activity. Preferably, a narrow temperature range, such as 30-40° C., should be used to avoid denaturing the enzyme. The optimum working conditions when Savinase™ is the chosen enzyme are 57° C. and pH 9-11. The enzymic extraction should be carried out for at least 45 minutes; any shorter duration is believed to be insufficient for a proteolytic enzyme to degrade tobacco proteins.

Of course, multiple enzymic extractions could be carried out if there are multiple constituents to be removed from the tobacco. These could be performed in series or multiple enzymes could be added to the tobacco in a single treatment step.

It also remains possible for the enzyme to be included in the very first extraction step in the treatment process, rather than forming a subsequent separate extraction step.

Following enzymic extraction, the insoluble tobacco residue may be washed with a salt solution, preferably a sodium chloride solution, to rinse it free of enzyme. Salt rinsing may be performed in a sequential, counter-current fashion.

Salt and water rinsing, however, may not be sufficient to remove all of the enzyme from the tobacco. The washed tobacco may also be treated to deactivate any residual enzyme remaining in the tobacco following the salt and water rinses. This may be done by steam treating the tobacco sufficiently to deactivate the enzyme, but not so much that the tobacco loses its fibrous form. In an embodiment, steam treating is carried out at about 98° C. for about four minutes, but the residence time may be increased to about 10 minutes if desired. Alternatively, the tobacco may be heat treated to deactivate the enzyme, for example by microwaving or baking the tobacco. In another embodiment, the enzyme may be deactivated by chemical denaturation; steps should however be taken to remove the chemical from the tobacco.

The processed tobacco may then be recombined with the concentrated tobacco extract. Adding the treated extract back to the extracted tobacco ensures retention of water soluble flavour components of tobacco and nicotine in the final product. Recombination therefore results in a tobacco product that has similar physical form and appearance, taste and smoking properties to the original material, but with substantially reduced levels of protein, polyphenols or other constituent(s) of choice. Recombination may be achieved by spraying the tobacco extract onto the tobacco. The amount of the original extract being recombined with the processed tobacco depends upon the amount that was lost during treatment of the extract to remove selected constituents, and will vary from one type of tobacco to the next.

A standard drying process may be used to dry the treated tobacco, either before, during or after recombination with the treated tobacco extract. The starting moisture content of the treated tobacco is typically approximately 70-80%. In a preferred embodiment, the moisture content after drying should be approximately 14%. A heated dryer, such as an apron dryer, may be used to reduce the starting moisture content in the tobacco to approximately 30%. A second heated dryer, such as an air dryer, may then be used to further reduce the moisture content to approximately 14%.

The final dried product may subsequently be processed into a finished form, such as a sheet, which, when shredded, can form all or part of a cigarette filler. Owing to as much as 30% of the original constituents of tobacco being removed therefrom during the extraction and treatment process, however, the concentration of remaining constituents per unit weight of tobacco is increased in the finished product compared to the original material. These constituents include cellulose, which, together with sugars and starches, may produce harmful volatile materials such as acetaldehyde and formaldehyde in smoke when combusted.

Another approach to reducing smoke toxicant yields is to dilute the smoke with glycerol and this may be done by forming a so-called “tobacco substitute sheet” (TSS) which includes a large proportion of glycerol, for example up to 60% by weight of a glycerol. Analysis of mainstream smoke from cigarettes included such TSS in the smokeable material showed reductions in yields of most measured constituents, other than some volatile species.

In some embodiments of the invention, the smokeable material comprises a tobacco substitute sheet.

Incorporation of the tobacco substitute sheet (TSS) into a tobacco blend reduces the quantity of tobacco in a cigarette, thereby further diminishing the overall potential for the cigarette to generate toxicants. When heated, the glycerol included in the TSS releases into the smoke stream contributing to the total amount of particulate smoke, measured as nicotine-free dry particulate matter (NFDPM, also known as “tar”). As most cigarettes are designed to meet a specific NFDPM yield value, incorporation of glycerol into the smoke stream effectively results in a reduced contribution of the tobacco combustion products to the overall NFDPM value: this process is termed “dilution”. The incorporation of TSS into smoking articles results in reductions in a wide range of smoke constituents, including both particulate and vapour phase toxicants. In vitro toxicological tests showed reductions in the activity of smoke particulates in proportion to their glycerol content. Human exposure to nicotine was reduced by a mean of 18% as determined by filter studies and by 14% using 24 hour urinary biomarker analysis. Smoke particulate exposures were reduced by a mean of 29% in filter studies and by similar amounts based on urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol concentrations. These results show that reducing exposure to some smoke toxicants is possible using a tobacco substitute sheet.

In some embodiments, the smoking article includes a tobacco substitute sheet material comprising a non-combustible inorganic filler material, a binder (such as, for example, and alginic binder) and aerosol generating means.

Advantageously the tobacco substitute sheet material comprises as the main components thereof, non-combustible inorganic filler, binder and aerosol generating means, with these three components together preferably comprising at least 85% by weight of the tobacco substitute sheet material, preferably greater than 90%, and even more preferably total about 94% or more by weight of the tobacco substitute sheet material. The three components may even be 100% of the tobacco substitute sheet material. The remaining components are preferably one or more of colorant, fibre, such as wood pulp, or flavourant, for example. Other minor component materials will be known to the skilled man. The tobacco substitute sheet material is therefore a very simple sheet in terms of its constituents.

As used herein, the term′ tobacco substitute sheet material′ means a material which can be used in a smoking article. It does not necessarily mean that the material itself will necessarily sustain combustion. The tobacco substitute sheet material is usually produced as a sheet, then cut. The tobacco substitute sheet material may then be blended with other materials to produce a smokeable filler material.

In some embodiments, a smoking article comprises a wrapped rod of a smokeable filler material, the smokeable filler material consisting of a blend which incorporates tobacco substitute sheet material comprising a non-combustible inorganic filler, an alginic binder and aerosol generating means, the smoking article having an aerosol transfer efficiency ratio of greater than 4.0. As used herein, the aerosol transfer efficiency is measured as the percentage aerosol in the smoke divided by the percentage aerosol in the smokeable filler material. Preferably the aerosol transfer efficiency is greater than 5, and more preferably greater than 6.

The smokeable material used in the smoking articles of the present invention may comprise a blend consisting of not more than 75% by weight of the tobacco substitute sheet material.

Preferably the inorganic filler material is present in the range of 60-90%, and is more preferably greater than 70% of the final sheet material. Advantageously the inorganic filler material is present at about 78% by weight of the final sheet material, but may be present at higher levels, for example, 80%, 85% or 90% by weight of the final sheet material.

In some embodiments, the non-combustible filler advantageously comprises a proportion of material having a mean particle size in the range of 500 μm to 75 μm or in the range of 400 μm to 100 μm, a mean particle size of more than 125 μm, or more than 150 μm. In some cases, it may be advantageous for the mean particle size to be about 170 μm, or in the range of 170 μm to 200 μm. This particle size is in contrast to that conventionally used for food grade inorganic filler materials in alternative tobacco products, namely a particle size of about 2-3 μm. The range of particle size seen for each inorganic filler individually may be from 1 μm-1 mm (1000 μm). The inorganic filler material may be ground, milled or precipitated to the desired particle size.

The inorganic filler material may be one or more of perlite, alumina, diatomaceous earth, calcium carbonate (chalk), vermiculite, magnesium oxide, magnesium sulphate, zinc oxide, calcium sulphate (gypsum), ferric oxide, pumice, titanium dioxide, calcium aluminate or other insoluble aluminates, or other inorganic filler materials. The density range of the materials may be in the range of 0.1 to 5.7 g/cm³. In some embodiments, the inorganic filler material has a density that is less than 3 g/cm³, less than 2.5 g/cm³, less than 2.0 g/cm³ or less than 1.5 g/cm³. An inorganic filler having a density of less than 1 g/cm³ may be desirable. A lower density inorganic filler reduces the density of the product, thus improving the ash characteristics.

If a combination of inorganic filler materials is used, one or more of the fillers may suitably be of a small particle size and another may be of a larger particle size, the proportions of each filler being suitable to achieve the desired mean particle size. The static burn rate required in the finished smoking article may be achieved using an appropriate blend of tobacco and tobacco substitute sheet material in the smokeable filler material.

In some embodiments, the inorganic filler material is not in agglomerated form. The inorganic filler material should require little pre-treatment, other than perhaps size gradation, before use. The binder may be present in the range of about 5-13%, less than 10% or less than 8%, by weight of the final filler material. The binder may be about 7.5% by weight or less of the final sheet material. If the binder is a mixture of alginate and non-alginate binders, then the binder may comprise at least 50% alginate, at least 60% alginate or at least 70% alginate. The amount of combined binder required may suitably decrease when a non-alginate binder is utilised. The amount of alginate in a binder combination advantageously increases as the amount of combined binder decreases. Suitable alginic binders include soluble alginates, such as ammonium alginate, sodium alginate, sodium calcium alginate, calcium ammonium alginate, potassium alginate, magnesium alginate, triethanol-amine alginate and propylene glycol alginate. Other organic binders such as cellulosic binders, gums or gels can also be used in combination with alginic binders. Suitable cellulosic binders include cellulose and cellulose derivatives, such as sodium carboxymethylcellulose, methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose or cellulose ethers. Suitable gums include gum arabic, gum ghatti, gum tragacanth, Karaya, locust bean, acacia, guar, quince seed or xanthan gums. Suitable gels include agar, agarose, canageenans, furoidan and furcellaran. Starches can also be used as organic binders. Other suitable gums can be selected by reference to handbooks, such as Industrial Gums, E. Whistler (Academic Press). Much preferred as the major proportion of the binder are alginic binders. Alginates are preferred in the invention for their neutral taste character upon combustion.

In some embodiments, the aerosol generating means is present in the range of 5-20%, or is included in an amount less than 15%, greater than 7% and/or greater than 10%. In a particular embodiment, the aerosol generating means is included in an amount of less than 13%. In embodiments, the aerosol generating means is between 11% and 13%, or is about 11.25% or 12.5%, by weight of the final sheet material. Suitably the amount of aerosol generating means is selected in combination with the amount of tobacco material to be present in the blend comprising the smokeable filler material of a smoking article. For example, in a blend comprising a high proportion of sheet material with a low proportion of tobacco material, the sheet material may require a lower loading level of aerosol generating means therein. Alternatively in a blend comprising a low proportion of sheet material with a high proportion of tobacco material, the sheet material may require a higher loading level of aerosol generating means therein.

Suitable aerosol generating means include aerosol forming means selected from polyhydric alcohols, such as glycerol, propylene glycol and triethylene glycol; esters, such as triethyl citrate or triacetin, high boiling point hydrocarbons, or non-polyols, such as glycols, sorbitol or lactic acid, for example. A combination of aerosol generating means may be used.

An additional function of the aerosol generating means is the plasticising of the sheet material. Suitable additional plasticisers include water. The sheet material may suitably be aerated. The cast slurry thereby forms a sheet material with a cellular structure.

Advantageously the or a proportion of the aerosol generating means may be encapsulated, preferably micro-encapsulated, or stabilised in some other way. In such cases the amount of aerosol generating means may be higher than the range given.

Advantageously the smoking material comprises a colorant to darken the material and/or a flavourant to impart a particular flavour. Suitable colorant materials, subject to local regulations, can include molasses and malt extract, for example. Finely ground, granulated or homogenised tobacco may also be used. Industry approved food colorants may also be used, such as E150a (caramel), E151 (brilliant black BN), E153 (vegetable carbon) or E155 (brown HT). Suitable flavourants include menthol and vanillin, for example. Other casing materials may also be suitable. In the alternative, the presence of vermiculite or other inorganic filler materials may give a darker colour to the tobacco substitute sheet material. The colorant may be present from 0-10% and may be as much as 5-7% by weight of the final tobacco substitute sheet material. In some embodiments, the colorant is less than 7%, less than 6% or less than 5% of the final tobacco substitute sheet material. In some embodiments, the amount of colorant used is less than 4%, less than 3% or less than 2%. For example, caramel may suitably be present in a range of 0-5%, or less than about 2% by weight of the final tobacco substitute sheet material, or about 1.5%. Other suitable colorants include molasses, malt extract, coffee extract, tea resinoids, St. John's Bread, prune extract or tobacco extract. Mixtures of colorants may also be used.

If permitted under local regulations, flavourants may also be added to alter the taste and flavour characteristics of the tobacco substitute sheet material. Advantageously, if a food dye is utilised in the alternative it is present at 0.5% by weight or less of the final tobacco substitute sheet material. The colorant may alternatively be dusted into the sheet after sheet manufacture.

Fibres, such as cellulose fibres, for example wood pulp, flax, hemp or bast could be added to provide the sheet material with one or more of a higher strength, lower density or higher fill value. Fibres, if added, may be present in the range of 0.5-10%, in an amount of less than 5% or less than about 3% by weight of the final sheet material. Advantageously there is no fibrous material present in the sheet material, cellulosic or otherwise.

In some embodiments, the tobacco substitute sheet material is a non-tobacco containing sheet. It shall be understood that at high levels of sheet material inclusion in the blend, e.g. at greater than 75% by weight of the blend, the combustibility of the blend is poor. This may be overcome by, for example, incorporating low levels of up to 5-10% granular carbon in the tobacco substitute sheet material. The carbon is preferably not an agglomerated carbonaceous material, i.e. the carbon is not pre-treated by mixing with another material to produce an agglomerate.

In some embodiments, the tobacco substitute sheet material is blended with tobacco material to provide smokeable filler material. Preferably the tobacco material components in the blend are high quality lamina grades. Advantageously the majority of the tobacco material is cut tobacco. The tobacco material may comprise between 20-100% expanded tobacco of a high order expansion process, such as DIET for example. The filling power of such material is typically in the range of 6-9 cc/g (see GB 1484536 or U.S. Pat. No. 4,340,073 for example).

In some embodiments, the blend comprises less than 30% of other blend components apart from lamina, the other blend components being stem cut rolled stem (CRS), water treated stem (WTS) or steam treated stem (STS) or reconstituted tobacco. The other components may comprise less than 20%, less than 10% or less than 5% of the final weight of the tobacco material.

In some embodiments, a smoking article according to the invention comprises tobacco material treated with aerosol generating means. The tobacco material may be treated with aerosol generating means, but this is not essential for all blends of tobacco material and sheet material.

The amount of aerosol generating means added to the tobacco is in the range of 2-6% by weight of the tobacco. The total amount of aerosol generating means in the blend of tobacco material and sheet material after processing is advantageously in the range of 4-12% by weight of the smokeable material, preferably less than 10% and preferably more than 5% on a dry wt/wt basis.

In one embodiment, glycerol is added to the smokeable material comprising tobacco substitute sheet. This has been found to lead to a reduction in the level of some phenols. The glycerol may be added in an amount of about 1% by weight (in addition to any glycerol that might be included in the tobacco substitute sheet). It is believed that adding the glycerol to the TSS may be having a synergistic effect.

In some embodiments, the blend may also include a top flavour in order to improve the aroma and sensory performance of the blend.

A yet further approach to reducing smoke toxicant yields in the smoking articles of the present invention is to select tobacco blend components that exhibit low levels of the precursors of undesirable smoke constituents, such as TSNAs and metals. For example, the levels of TSNAs may be reduced by using specific (such as lighter) tobacco blends and by selecting parts of the tobacco plant that are low in nitrate, a precursor of TSNAs. In some embodiments, this involves using tobacco lamina. The person skilled in the art would be well aware of the ways in which the blending process may be adapted to provide a tobacco blend having these desired properties.

The tobacco blend may also comprise expanded tobacco, which is cut tobacco that has been expanded to reduce the mass of tobacco burnt in a cigarette One process used to process tobacco is called dry-ice expanded tobacco (DIET). The tobacco is infused with liquid carbon dioxide (CO₂), in a pressure vessel, the pressure is lowered and the liquid CO₂ drained off, resulting in solid CO₂ or dry ice forming within the cellular structure of the tobacco. The tobacco is then heated quickly forcing the dry ice into gaseous CO₂, which forces the structure of the cut tobacco leaf to expand to a volume which is closer to that of the leaf before the curing process. Expanded tobacco is widely used in commercial cigarettes and even more so in those of low ISO yields.

In one embodiment of the invention, the smokeable material is made up of a blend of 50% blend treated tobacco (BTT), 15% tobacco substitute sheet (TSS), 10% dry-ice expanded tobacco (DIET) and 25% Lamina, with addition of 1% glycerol and 0.8% of an added top flavour.

The above discussed filter and smokeable material technologies work in combination to provide a smoking article with substantial reductions in smoke toxicant levels.

In some embodiments, the smoking articles according to the invention have a reduction (for example, compared to a conventional cigarette) in at least 75%, at least 90%, at least 95% or in all of the key constituents of mainstream smoke, as defined herein.

The so-called “key constituents” of MS referred to in connection with the present invention are those smoke constituents which have been identified in the literature as being undesirable (see, for example, The Scientific Basis of Tobacco Product Regulation: Report of a WHO Study Group (2007) WHO Technical Report Series 945, Geneva).

The reduction is preferably determined using an intense smoking regime where the ventilation is left open, as products have been designed to match at ISO and the ventilation blocking of the Health Canada regime negates the effect of the split tip.

The reduction in yield of the key constituents is preferably at least 5% or at least 10% or more.

Examples

The specifications of some examples of smoking articles according to embodiments of the present invention are set out in the tables below. Two prototypes are described; one is to deliver 1 mg of tar, the other 7 mg of tar. “Cig.” is used as an abbreviation for “cigarette”.

TABLE 1 Smoking article characteristics 1 mg Prototype 7 mg Prototype Parameter Type Unit Target Target Cigarette length mm 83 83 Cig. circumference mm 21.0 21.0 Filter length mm 37 37 Tipping width (pre- mm 64 64 slitting) In-pack moisture (for % 12.0 12.0 tobacco weight) Density (at in-pack mg/cm³ 305 305 moisture) Tobacco weight (at in- mg 490 490 pack moisture) Weight cig. paper + mg 25 25 adhesive Weight applied cig. mg 3.9 3.9 flavour Rod weight (at in-pack mg 512 512 moisture) Weight filter tip mg 283 283 Total cig. weight (at in- mg 818 818 pack moisture) Non tobacco weight mg 332 332 Filter ventilation % 80 40 Ventilation type Split tipping and Split tipping and On Machine On Machine Laser Laser On-line laser position mm 13 13 Cig. pressure drop (open) mmWG 165 130 Filter plug pressure drop mmWG 135 110 (enc) Ends stability mg/end <8 <8 Cig. Firmness % ≧72 ≧72 Tar mg 1.0 7.0 Nic mg 0.1 0.7 CO mg 1.0 7.0 Puff Number 7.2 7.4

TABLE 2 Cigarette paper characteristics 1 mg Prototype 7 mg Prototype Parameter Type Unit Target Target Name (LIPtech) CP50- (LIPtech) CP50- 23VGM2.0KCW 23VGM1.0KCW Supplier Glatz Glatz Bobbin Width mm 23 23 Fibre Wood Wood Permeability CU 50 50 Thickness μm 40 40 Grammage g/m² 23 23 Burn additive Type Potassium Citrate Potassium Citrate Burn Additive content %   2.0   1.0 CaCO₃ content % 30 30

TABLE 3 Tipping paper characteristics 1 mg Prototype 7 mg Prototype Parameter Type Unit Target Target Name MLO3345146 MLO3345146 Supplier Benkert Benkert Width post machine slitting mm 21/11 21/11 Porosity CU  0  0 Type of perforation OML + ST OML + ST Thickness μm 50 50 Grammage g/m² 42 42

TABLE 4 Filter materials for 7 mg version (440 mm Wg) Com- Middle ponent Overall Mouth end section Tobacco end Base rod THS ABR060414 AAS060501 AAS060502 name 100600 Tow N/A 8.0Y/28000 9.0Y/25000 9.0Y/25000 Rhodia Rhodia Rhodia Plug wrap CP200- 23.0 mm 23.0 mm 23.0 mm OU 0.4 12000CU 12000CU 12000CU KCW Wattens Wattens Wattens Plasticiser N/A Triethylcitrate Triethylcitrate Triethylcitrate Adhesive 072-0143 072-0143 072-0143 072-0143 anchorage Henkel Henkel Henkel Henkel Adhesive 5675A/ 334-2950 334-2950 334-2950 seam 1 B Forbo Tobacoll Tobacoll Tobacoll Additive N/A N/A AFR HAC Additive 70 0 20 50 weight (mg)

TABLE 5 Filter materials for 1 mg version (540 mm Wg) Com- Middle ponent Overall Mouth end section Tobacco end Base rod THS ABR060414 AAS060501 AAS060503 name 100601 Tow N/A 8.0Y/28000 9.0Y/25000 5.0Y/25000 Rhodia Rhodia Rhodia Plug wrap CP200- 23.0 mm 23.0 mm 23.0 mm OU 0.4 12000CU 12000CU 12000CU KCW Wattens Wattens Wattens Plasticiser N/A Triethylcitrate Triethylcitrate Triethylcitrate Adhesive 072-0143 072-0143 072-0143 072-0143 anchorage Henkel Henkel Henkel Henkel Adhesive 5675A/B 334-2950 334-2950 334-2950 seam 1 Forbo Tobacoll Tobacoll Tobacoll Additive N/A N/A CR20D Synthetic Carbon resin Additive 70 0 20 50 weight (mg)

Table 6 summarises recognised machine smoking regimes used to generate smoke data.

TABLE 6 Smoking machine parameters Filter Puff Puff Puff Vent Smoking Volume Duration Interval Blocking Description Abbreviation (ml) (s) (s) (%) ISO 3308/4387 ISO 35 2 60 0 Health Canada HCI 55 2 30 100 Intense ISO WG 9 WG9B 60 2 30 50 Intense Option B

Table 7 shows the yields for the 7 mg test product under both ISO and WG9 machine smoking regimes and includes the ratios of WG9 to ISO. Table 8 provides corresponding information relating to the control/comparator cigarette. The data from both tables show that the ratios of WG9:ISO yields tend to be greater for the control product over those of the test product. This is as predicted due to the reduction in ventilation achieved at the higher cigarette puff volume (of the same puff duration), when smoking the test product using WG9 regime (where half vent holes and ST are occluded). This is therefore flow rate dependent and not volume dependent. If none of the ventilation holes and split tip ventilation were occluded the yields of the test product would be even lower at higher puff volume.

TABLE 7 Mainstream smoke data for 7 mg test product at ISO and WG9 smoke regimes Sample number G429 G429 Sample Description 7 mg Test 7 mg Test ST + OML ST + OML Smoke Regime MS Data ISO WG9 Ratio (Labstat) Units Mean SD Mean SD WG9:ISO Puff count 7.6 0.3 10.0 0.3 NFDPM mg/cig 6.4 0.3 16.2 0.5 2.5 Nicotine mg/cig 0.64 0.03 1.45 0.04 2.3 CO mg/cig 5.4 0.3 14.0 0.3 2.6 NO  μg/cig 31.3 2.9 85.0 9.0 2.7

TABLE 8 Mainstream smoke data for 7 mg control product at ISO and WG9 smoke regimes Sample Number H285 H285 Sample Description 7 mg Control 7 mg Control OML OML Smoking Regime MS Data ISO WG9 Ratio (Labstat) Units Mean SD Mean SD WG9:ISO Puff count 7.2 0.2 9.0 0.4 NFDPM mg/cig 7.1 0.4 23.9 2.4 3.4 Nicotine mg/cig 0.58 0.04 1.52 0.14 2.6 CO mg/cig 7.4 0.4 22.4 0.8 3.0 NO  μg/cig 88.5 4.7 234.1 14.4 2.6

Examples of the reductions in the smoke yields, both in absolute terms and ‘normalised’ to NFDPM (Tar) and Nicotine, using the HCI smoking regime are shown in Table 9. Note that under the HCI regime the use of the split tipping technology does not contribute to the reductions in smoke component yields obtained for the smoking article according to the invention relative to the comparator/control.

TABLE 9 Mainstream data for test and control cigarettes at HCI smoking regime Sample Number G429 H285 Sample Description 7 mg Test 7 mg Control Absolute ST + OML OML change Change Change Smoking Regime wrt wrt wrt MS Data HCI HCI Control NFDPM Nicotine (Labstat) Units Mean SD Mean SD % % % Puff count 9.1 0.5 8.2 0.3 NFDPM mg/cig  17.8 1.2 26.3 1.7 Nicotine mg/cig  1.48 0.06 1.59 0.04 CO mg/cig  15.7 0.8 22.7 1.1 −30.8 2.2 −25.7 NNN ng/cig 25.4 2.0 171.4 8.2 −85.2 −78.1 −84.1 NNK ng/cig 28.3 2.8 79.9 2.9 −64.5 −47.6 −61.9 Formaldehyde μg/cig 48.6 4.3 64.4 7.9 −24.6 11.5 −19.0 Acetaldehyde μg/cig 576 36 1122 40 −48.6 −24.1 −44.8 Acrolein μg/cig 61.6 5.5 137.0 5.3 −55.0 −33.5 −51.7 B[a]P ng/cig 13.6 0.9 18.5 1.8 −26.4 8.8 −20.9 Benzene μg/cig 9.7 1.1 68.5 3.9 −85.9 −79.1 −84.8 1,3 Butadiene μg/cig 52.5 2.8 95.3 3.5 −44.9 −18.6 −40.8 Test versus Control data: Negative (−) values = Reductions; Positive values = Increases

Examples of the reductions in the smoke yields, both in absolute terms and ‘normalised’ to NFDPM (Tar) and Nicotine, using the WG9 smoking regime are shown in Table 10. Under the WG9 regime the use of the split tipping technology does contribute to the reductions in smoke component yields obtained for the smoking article according to the invention relative to the comparator.

TABLE 10 Mainstream data for test and control cigarettes at WG9 smoking regime Sample Number G429 H285 Sample Description 7 mg Test 7 mg Control Absolute ST + OML OML change Change Change Smoking Regime wrt wrt wrt MS Data WG9 WG9 Control NFDPM Nicotine (Labstat) Units Mean SD Mean SD % % % Puff count 10.0 0.3 9.0 0.4 NFDPM mg/cig  16.2 0.5 23.9 2.4 Nicotine mg/cig  1.45 0.04 1.52 0.14 CO mg/cig  14.0 0.3 22.4 0.8 −37.5 −7.8 −34.5 NNN ng/cig 22.8 2.8 143.9 9.2 −84.2 −76.6 −83.4 NNK ng/cig NQ NQ 70.9 4.5 >95.0 >95.0 >95.0 Formaldehyde μg/cig 49.9 5.3 54.1 10.8 −7.6 36.3 −3.1 Acetaldehyde μg/cig 434 33 959 80 −54.7 −33.2 −52.5 Acrolein μg/cig 44.8 2.9 120.6 13.1 −62.8 −45.2 −61.0 B[a]P ng/cig 13.1 0.7 17.3 1.8 −24.2 11.9 −20.5 Benzene μg/cig 9.5 1.3 63.6 6.2 −85.1 −78.0 −84.4 1,3 Butadiene μg/cig 47.6 5.0 89.9 5.0 −47.1 −21.9 −44.5 Test versus Control data: Negative (−) values = Reductions; Positive values = Increases

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention may be practiced and provide for superior smoking articles. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations within the scope of the appended claims and equivalents thereof. 

1. A smoking article, comprising: a smokeable material rod; a filter attached to one end of the smokeable material rod, said filter including at least two sections and a porous plug wrap; a first tipping wrapper overlying a join between the smokeable material rod and the filter, thereby attaching the filter to the smokeable material rod; and at least one further tipping wrapper disposed around the filter, spaced from and separate from the first tipping wrapper such that a portion of the porous plug wrap is exposed between the first tipping wrapper and the at least one further tipping wrapper, and wherein the first tipping wrapper and the at least one further tipping wrapper are each less porous than the plug wrap.
 2. The smoking article as claimed in claim 1, wherein a gap is formed between the first tipping wrapper and the at least one further tipping wrapper, the gap exposing an area of the filter that is surrounded with a material that is more porous than each of the first tipping wrapper and the at least one further tipping wrapper, such that a section of the filter is surrounded only by the porous plug wrap.
 3. The smoking article as claimed in claim 1, wherein at least one filter section comprises a fibrous filter material.
 4. The smoking article as claimed in claim 1, wherein at least one filter section comprises a porous adsorbent material.
 5. The smoking article as claimed in claim 4, wherein the porous adsorbent material is a porous carbon having an engineered porous structure.
 6. The smoking article as claimed in claim 4, wherein the at least one filter section includes from about 20 mg to about 80 mg porous adsorbent material.
 7. The smoking article as claimed in claim 1, wherein at least one filter section comprises an ion exchange resin.
 8. The smoking article as claimed in claim 7, wherein the ion exchange resin has a surface activated amine.
 9. The smoking article as claimed in claim 7, wherein the filter section includes from about 5 mg to about 40 mg ion exchange resin.
 10. The smoking article as claimed in claim 1, wherein the at least two sections of the filter include: a mouth end section having a fibrous filter material, a section comprising an ion exchange resin, and a section comprising porous adsorbent material adjacent to the smokeable material rod.
 11. The smoking article as claimed in claim 1, wherein the filter has a length from about 30 mm to about 40 mm.
 12. The smoking article as claimed in claim 1, wherein the smoking article has a length of about 83 mm and/or a circumference of about 21 mm.
 13. The smoking article as claimed in claim 1, wherein a separation between the first tipping wrapper and the at least one further tipping wrapper is about 10 mm.
 14. The smoking article as claimed in claim 1, wherein a tipping wrapper and/or a body of the filter define ventilation holes therein.
 15. The smoking article as claimed in claim 1, wherein the smokeable material rod includes one or more of: (a) a tobacco treated to produce reduced levels of nitrogenous compounds; (b) a tobacco treated to remove polyphenols and/or peptides; and (c) a tobacco substitute sheet comprising a non-combustible inorganic filler, a binder and an aerosol generator.
 16. The smoking article as claimed in claim 15, wherein the smokeable material rod further comprises lamina tobacco.
 17. The smoking article as claimed in claim 15, wherein the smokeable material rod further comprises dry ice expanded tobacco (DIET).
 18. The smoking article as claimed in claim 1, wherein the smokeable material rod comprises glycerol.
 19. The smoking article as claimed in claim 1, wherein the smokeable material rod comprises at least one flavor.
 20. The smoking article as claimed in claim 1, wherein the smokeable material rod comprises a blend treated tobacco, tobacco substitute sheet, DIET, lamina tobacco, glycerol and a top flavour.
 21. The smoking article as claimed in claim 4, wherein the porous adsorbent material is a synthetic source-derived porous carbon bead.
 22. The smoking article as claimed in claim 4, wherein the porous adsorbent material is a polystyrene-derived porous carbon bead.
 23. The smoking article as claimed in claim 11, wherein the filter has a length of about 37 mm. 